C# Mongo FirstOrDefaultAsync hangs

问题

using the 2.0 driver the following code will sometimes hang and never return.

public async Task<T> GetFirst(FilterDefinition<T> query)
{
    return await GetCollection.Find(query).FirstOrDefaultAsync();
}

if I debut and put a break point on the return line, everything returns normally. In the shell the query being run is something like this:

db.Customers.find({"Name" : /test$/i})

回答1:

There are 2 solutions:

1. Add a ConfigureAwait(false) at the end:

   return await GetCollection.Find(query).FirstOrDefaultAsync().ConfigureAwait(false);
   

2. Just return the Task<T>, since the result of FirstOrDefaultAsync() is the same type as the result you want to return.

   public Task<T> GetFirst(FilterDefinition<T> query)
   {
       return GetCollection.Find(query).FirstOrDefaultAsync();
   }
   

来源：https://stackoverflow.com/questions/29656923/c-sharp-mongo-firstordefaultasync-hangs